The use of natural products, including proteins, is a well known method of controlling many insect pests. For example, endotoxins of Bacillus thuringiensis (B.t.) are used to control both lepidopteran and coleopteran insect pests. Genes producing these endotoxins have been introduced into and expressed by various plants, including cotton, tobacco, tomato, and maize. There are, however, several economically important insect pests that are not susceptible toB.t. endotoxins, including the boll weevil, Anthonomus grandis, and corn rootworm (CRW), Diabrotica spp. In addition, having other, different gene products for control of insects which are susceptible toB.t. endotoxins is critical for resistance management.
Several other known insecticidal proteins are found in plants. These include lectins, amylase inhibitors, and protease inhibitors, which can affect insect growth and development when ingested at high levels. See, e.g., Boulter et al., 1989; Broadway and Duffey, 1986, Czapla and Lang, 1990; Gatehouse et al., 1986, Heusing et al., 1991; Ishimoto and K. Kitamura, 1989, Murdock et al., 1990; Shuckle and Murdock, 1993. However, these proteins apparently do not provide the acute mortality afforded by B.t proteins.
Patatins are a family of proteins found in potato (see Gaillaird, 1971; Racusen, 1984; Andrews et al., 1988) and other plants, particularly in solanaceous plants (Ganal et al., 1991; Vancanneyt et al., 1989). In potato the patatins are found primarily in tubers, but also at much lower levels in other plant organs (Hofgen and Willmitzer, 1990). Genes that encode patatins have been isolated. See, e.g., Mignery et al., 1984; Mignery et al., 1988; Stiekema et al., 1988. Roshal et al., 1987, transferred a patatin gene to tobacco and expressed patatin in transgenic tobacco plants.
Although the benefits of expression of heterologous genes in transgenic plants cannot be minimized, there are additional benefits to be gained from discovering native or autologous genes, the copy number of which and/or the expression of which can be increased. In addition, even when a heterologous gene is inserted into and expressed in transgenic plants, if that gene is isolated from a somewhat more closely related species, its expression level may be higher than in instances where genes from unrelated species are used, and its expression product may be more effective. Therefore, an effective insect control protein from an agronomic crop species is highly desirable.